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openssh-portable/bitmap.c

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/*
* Copyright (c) 2015 Damien Miller <djm@mindrot.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include "bitmap.h"
#define BITMAP_WTYPE u_int
#define BITMAP_MAX (1<<24)
#define BITMAP_BYTES (sizeof(BITMAP_WTYPE))
#define BITMAP_BITS (sizeof(BITMAP_WTYPE) * 8)
#define BITMAP_WMASK ((BITMAP_WTYPE)BITMAP_BITS - 1)
struct bitmap {
BITMAP_WTYPE *d;
size_t len; /* number of words allocated */
size_t top; /* index of top word allocated */
};
struct bitmap *
bitmap_new(void)
{
struct bitmap *ret;
if ((ret = calloc(1, sizeof(*ret))) == NULL)
return NULL;
if ((ret->d = calloc(1, BITMAP_BYTES)) == NULL) {
free(ret);
return NULL;
}
ret->len = 1;
ret->top = 0;
return ret;
}
void
bitmap_free(struct bitmap *b)
{
if (b != NULL && b->d != NULL) {
memset(b->d, 0, b->len);
free(b->d);
}
free(b);
}
void
bitmap_zero(struct bitmap *b)
{
memset(b->d, 0, b->len * BITMAP_BYTES);
b->top = 0;
}
int
bitmap_test_bit(struct bitmap *b, u_int n)
{
if (b->top >= b->len)
return 0; /* invalid */
if (b->len == 0 || (n / BITMAP_BITS) > b->top)
return 0;
return (b->d[n / BITMAP_BITS] >> (n & BITMAP_WMASK)) & 1;
}
static int
reserve(struct bitmap *b, u_int n)
{
BITMAP_WTYPE *tmp;
size_t nlen;
if (b->top >= b->len || n > BITMAP_MAX)
return -1; /* invalid */
nlen = (n / BITMAP_BITS) + 1;
if (b->len < nlen) {
if ((tmp = reallocarray(b->d, nlen, BITMAP_BYTES)) == NULL)
return -1;
b->d = tmp;
memset(b->d + b->len, 0, (nlen - b->len) * BITMAP_BYTES);
b->len = nlen;
}
return 0;
}
int
bitmap_set_bit(struct bitmap *b, u_int n)
{
int r;
size_t offset;
if ((r = reserve(b, n)) != 0)
return r;
offset = n / BITMAP_BITS;
if (offset > b->top)
b->top = offset;
b->d[offset] |= (BITMAP_WTYPE)1 << (n & BITMAP_WMASK);
return 0;
}
/* Resets b->top to point to the most significant bit set in b->d */
static void
retop(struct bitmap *b)
{
if (b->top >= b->len)
return;
while (b->top > 0 && b->d[b->top] == 0)
b->top--;
}
void
bitmap_clear_bit(struct bitmap *b, u_int n)
{
size_t offset;
if (b->top >= b->len || n > BITMAP_MAX)
return; /* invalid */
offset = n / BITMAP_BITS;
if (offset > b->top)
return;
b->d[offset] &= ~((BITMAP_WTYPE)1 << (n & BITMAP_WMASK));
/* The top may have changed as a result of the clear */
retop(b);
}
size_t
bitmap_nbits(struct bitmap *b)
{
size_t bits;
BITMAP_WTYPE w;
retop(b);
if (b->top >= b->len)
return 0; /* invalid */
if (b->len == 0 || (b->top == 0 && b->d[0] == 0))
return 0;
/* Find MSB set */
w = b->d[b->top];
bits = (b->top + 1) * BITMAP_BITS;
while (!(w & ((BITMAP_WTYPE)1 << (BITMAP_BITS - 1)))) {
w <<= 1;
bits--;
}
return bits;
}
size_t
bitmap_nbytes(struct bitmap *b)
{
return (bitmap_nbits(b) + 7) / 8;
}
int
bitmap_to_string(struct bitmap *b, void *p, size_t l)
{
u_char *s = (u_char *)p;
size_t i, j, k, need = bitmap_nbytes(b);
if (l < need || b->top >= b->len)
return -1;
if (l > need)
l = need;
/* Put the bytes from LSB backwards */
for (i = k = 0; i < b->top + 1; i++) {
for (j = 0; j < BITMAP_BYTES; j++) {
if (k >= l)
break;
s[need - 1 - k++] = (b->d[i] >> (j * 8)) & 0xff;
}
}
return 0;
}
int
bitmap_from_string(struct bitmap *b, const void *p, size_t l)
{
int r;
size_t i, offset, shift;
u_char *s = (u_char *)p;
if (l > BITMAP_MAX / 8)
return -1;
if ((r = reserve(b, l * 8)) != 0)
return r;
bitmap_zero(b);
if (l == 0)
return 0;
b->top = offset = ((l + (BITMAP_BYTES - 1)) / BITMAP_BYTES) - 1;
shift = ((l + (BITMAP_BYTES - 1)) % BITMAP_BYTES) * 8;
for (i = 0; i < l; i++) {
b->d[offset] |= (BITMAP_WTYPE)s[i] << shift;
if (shift == 0) {
offset--;
shift = BITMAP_BITS - 8;
} else
shift -= 8;
}
retop(b);
return 0;
}
#ifdef BITMAP_TEST
/* main() test against OpenSSL BN */
#include <err.h>
#include <openssl/bn.h>
#include <stdio.h>
#include <stdarg.h>
#define LIM 131
#define FAIL(...) fail(__FILE__, __LINE__, __VA_ARGS__)
void
bitmap_dump(struct bitmap *b, FILE *f)
{
size_t i;
fprintf(f, "bitmap %p len=%zu top=%zu d =", b, b->len, b->top);
for (i = 0; i < b->len; i++) {
fprintf(f, " %0*llx", (int)BITMAP_BITS / 4,
(unsigned long long)b->d[i]);
}
fputc('\n', f);
}
static void
fail(char *file, int line, char *fmt, ...)
{
va_list ap;
fprintf(stderr, "%s:%d ", file, line);
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
fputc('\n', stdout);
/* abort(); */
exit(1);
}
static void
dump(const char *s, const u_char *buf, size_t l)
{
size_t i;
fprintf(stderr, "%s len %zu = ", s, l);
for (i = 0; i < l; i++)
fprintf(stderr, "%02x ", buf[i]);
fputc('\n', stderr);
}
int main(void) {
struct bitmap *b = bitmap_new();
BIGNUM *bn = BN_new();
size_t len;
int i, j, k, n;
u_char bbuf[1024], bnbuf[1024];
int r;
for (i = -1; i < LIM; i++) {
fputc('i', stdout);
fflush(stdout);
for (j = -1; j < LIM; j++) {
for (k = -1; k < LIM; k++) {
bitmap_zero(b);
BN_clear(bn);
/* Test setting bits */
if (i > 0 && bitmap_set_bit(b, i) != 0)
FAIL("bitmap_set_bit %d fail", i);
if (j > 0 && bitmap_set_bit(b, j) != 0)
FAIL("bitmap_set_bit %d fail", j);
if (k > 0 && bitmap_set_bit(b, k) != 0)
FAIL("bitmap_set_bit %d fail", k);
if ((i > 0 && BN_set_bit(bn, i) != 1) ||
(j > 0 && BN_set_bit(bn, j) != 1) ||
(k > 0 && BN_set_bit(bn, k) != 1))
FAIL("BN_set_bit fail");
for (n = 0; n < LIM; n++) {
if (BN_is_bit_set(bn, n) !=
bitmap_test_bit(b, n)) {
FAIL("miss %d/%d/%d %d "
"%d %d", i, j, k, n,
BN_is_bit_set(bn, n),
bitmap_test_bit(b, n));
}
}
/* Test length calculations */
if (BN_num_bytes(bn) != (int)bitmap_nbytes(b)) {
FAIL("bytes %d/%d/%d %d != %zu",
i, j, k, BN_num_bytes(bn),
bitmap_nbytes(b));
}
if (BN_num_bits(bn) != (int)bitmap_nbits(b)) {
FAIL("bits %d/%d/%d %d != %zu",
i, j, k, BN_num_bits(bn),
bitmap_nbits(b));
}
/* Test serialisation */
len = bitmap_nbytes(b);
memset(bbuf, 0xfc, sizeof(bbuf));
if (bitmap_to_string(b, bbuf,
sizeof(bbuf)) != 0)
FAIL("bitmap_to_string %d/%d/%d",
i, j, k);
for (n = len; n < (int)sizeof(bbuf); n++) {
if (bbuf[n] != 0xfc)
FAIL("bad string "
"%d/%d/%d %d 0x%02x",
i, j, k, n, bbuf[n]);
}
if ((r = BN_bn2bin(bn, bnbuf)) < 0)
FAIL("BN_bn2bin %d/%d/%d",
i, j, k);
if ((size_t)r != len)
FAIL("len bad %d/%d/%d", i, j, k);
if (memcmp(bbuf, bnbuf, len) != 0) {
dump("bbuf", bbuf, sizeof(bbuf));
dump("bnbuf", bnbuf, sizeof(bnbuf));
FAIL("buf bad %d/%d/%d", i, j, k);
}
/* Test deserialisation */
bitmap_zero(b);
if (bitmap_from_string(b, bnbuf, len) != 0)
FAIL("bitmap_to_string %d/%d/%d",
i, j, k);
for (n = 0; n < LIM; n++) {
if (BN_is_bit_set(bn, n) !=
bitmap_test_bit(b, n)) {
FAIL("miss %d/%d/%d %d "
"%d %d", i, j, k, n,
BN_is_bit_set(bn, n),
bitmap_test_bit(b, n));
}
}
/* Test clearing bits */
for (n = 0; n < LIM; n++) {
if (bitmap_set_bit(b, n) != 0) {
bitmap_dump(b, stderr);
FAIL("bitmap_set_bit %d "
"fail", n);
}
if (BN_set_bit(bn, n) != 1)
FAIL("BN_set_bit fail");
}
if (i > 0) {
bitmap_clear_bit(b, i);
BN_clear_bit(bn, i);
}
if (j > 0) {
bitmap_clear_bit(b, j);
BN_clear_bit(bn, j);
}
if (k > 0) {
bitmap_clear_bit(b, k);
BN_clear_bit(bn, k);
}
for (n = 0; n < LIM; n++) {
if (BN_is_bit_set(bn, n) !=
bitmap_test_bit(b, n)) {
bitmap_dump(b, stderr);
FAIL("cmiss %d/%d/%d %d "
"%d %d", i, j, k, n,
BN_is_bit_set(bn, n),
bitmap_test_bit(b, n));
}
}
}
}
}
fputc('\n', stdout);
bitmap_free(b);
BN_free(bn);
return 0;
}
#endif
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